The invention relates to a nozzle plate adapted for an ink-jet type recording apparatus and the surface treatment of the nozzle plate.
In an ink-jet type recording apparatus which records an image on a recording medium by ejecting ink droplets from a nozzle, there exists a problem in that, when a portion surrounding a nozzle is wetted by an ink, deviation in the direction of the flight of ink droplets occurs.
To address this type of problem, Unexamined Japanese Patent Publications (Kokai) Nos. Sho. 55-65564 and Sho. 57-107848 have proposed an apparatus in which water-repellency treatment is performed on the nozzle plate surface surrounding a nozzle thereby to suppress generation of such wetting by the ink. However it is difficult to restrict the treatment to the nozzle plate surface only. Unexamined Japanese Patent Publication (Kokai) No. Hei. 2-48953 discloses a method whereby a plate impregnated with a silicon water-repellent agent is employed to wipe the surface of a nozzle plate, or pressure is applied to the surface of the nozzle plate by a porous member impregnated with a water-repellent agent.
In this case, with the resulting lining of the inner portion of a nozzle by a portion of the water-repellent agent, when ink drops are ejected at high speed from the nozzle, they contact the water-repellent agent adhered to a portion of the inner surrounding surface of the nozzle and the problem of a marked disruption of the direction of the flight of the ink droplets occurs as before.
An object of the present invention, in view of the above-mentioned problem, is to provide a new nozzle plate capable of preventing the flight of ink droplets from deviating.
Another object of the invention is to provide a novel nozzle plate surface treatment method of forming a water-repellent coating on the surface of a nozzle plate while restricting the lining of the inside of the nozzle with the water-repellent material.
Namely, the nozzle plate to achieve the above object incorporates a water-repellent coating formed on the nozzle plate surface surrounding the nozzle hole in such a way as to leave a portion not exceeding 20% of the diameter of the nozzle hole uncoated. Further, the nozzle plate surface treatment method for this nozzle plate comprises a photosensitive resin material which can be hardened by exposure to a light source laminated on the nozzle plate surface, with at least one portion entering the inner portion of the nozzle, with the portion of the photosensitive resin directly above the nozzle being exposed to a light source from behind the nozzle plate with sufficient energy to harden a portion of a size at least that of the nozzle diameter, being no more than 40% larger than that of the nozzle diameter. Finally, with this portion of the photosensitive resin hardened, a water-repellent coating layer is formed on the surface of the nozzle plate, incorporating the shape of the hardened portion of photosensitive resin.